Shoe stiffener



Dec. 17, 1929. A. L. CLAPP SHQE STIFFENER Filed Sept. 12. 925

to saturate the fibrous material with glue and Patented Dec; 17, 1929UNITED STATES PATENT OFFICE ALBERT L. 'CLAI'I', OF DANVER-S,MASSACHUSETTS, ASSIGNOR TO BECKWITH MANU- FAGTURING COMPANY, OF BOSTON,MASSACHUSETTS, A CORPORATION OF MASSA- GHUSETTS- SHOE STIFFENERApplication filed September 12, 1923. Serial No. 662,223.

Shoe stiffeners are commonlyconstructed of fibrous sheet materialsaturated with thermo-plastic material, that is, material which is hardat atmospheric and body temperatures but which may be softened bysubjecting it to a moderate degree of heat. The

shoe stiflener is heated when being formedinto the shoe and thereafterbeing allowed to cool in proper shape, becomes stiffand rigid and sonormally remains during the life of the shoe. The thermo-plasticmaterial is frequently softened by the application of dry heat and it isoften found that when shoes having incorporated therein stifienerssaturated with such material are exposed to the sun, as for examplewhenondisplay in show windows, the relatively intense heat causes thematerial 'to soften sufficiently to permit the stifieners partially tocollapse, thus impairing both the appearance of the shoes and terialother material which may be softened only by the application of moistheat thereto, such material, for example, as water soluble gums orstiffening agents such as animal or fish glue. It has beenfoundimpracticable also with the tremo-plastic material. The

glue when used alone does not possess properties necessary for itssuccessful use as stiffenmg materlal for the fibrous base, slnce 1t 1seaslly cracked and pulverized andis not waterproof. It is found,however, that a from the opposite face throughout and covers the glue.

Referring to the accompanying drawing which conventionally illustrates,much enlarged, a piece of the finished material, the

felt sheet is indicated at 1, the .coating of glue applied to one facethereof and penetrating more or less between the adjacent fibers of thefelt at 2, and the thermo-plastic saturant permeating the felt at 3 andcoating the glue surface at 4.

It is found in practice that the portion of the material saturated andcoated with the .glue vis sufficiently stiff to cause the' shoestlfiener formed therefrom to retain its shape even when subjected todry heat sufficient to soften the thermo-plastic compound and to causethe stiffener, without the presence of the glue, to lose its shape. Butby subjecting the stiffener so treated to the action of both moistureand heat, the glue, together. with the thermo-plastic material, issoftened so that,

the stiffener is reduced to a limp or plastic condition where it can besuccessfully worked and shaped to the last.

Instead of animal glue, dextrine, starch, or other water soluble gumsmay also be used, but animal or fish glue has been found preferable. Thepresence of the thermo-plastic material also renders the stiffenerwaterproof, 'which it would not be by the use of glue alone, but theglue coating is covered with the thermo-plastic material in thesaturating process and so is sufficiently protected to render itwaterproof without causing it to be entirely inaccessible to the moistheat treatment to which it is subjected preparatory for the formingoperation about the last. Where the glue is used, Montan wax may beemployed as the thermo-plastic-saturant for a felt such as produced on apaper machine. Montan wax ordinarily can not be used satis= factorilyalone in the impregn ation of apaper felt where glue is not used, sinceit becomes so fluid, when heated sufficiently to soften it that it actsas a lubricant and permits the fibers of a felt, such as produced on apaper machine, to pull apart. The presence of the glue, however, holdsthe fibers together and retains the wax and so make it possible to usethis material alone as the thermo-plastic saturant.

By the treatment herein outlined, it "is seen that two stiffening agentsof different characteristics, one being softenable by dr heat and theother requiring moisture in a dition to heat, are employed in differentortions of the thickness of the fibrous s eet material, each respondingto heat treatment in its own way without modification by the other. Oneof these stiffenin heretofore described, may be incorporated while in anaqueous vehicle, the water then being dried out and this agent allowedto harden. The other agent ma then be incorporated when in melted conition. In the completed 'article the stiffness imparted by. each agentis reducible under its own particular conditions of softeningindependently of the other 'so that the stiffener must be subjected tothe conditions which will soften all the stiffening agents used in orderto render it limp.

I claim:

1. A shoe stiffener comprising fibrous sheet material having one portiontreated with a water soluble stiffening agent only and anotlier portionwith thermo-plastiematerial on y.

2. A shoe stiffener comprising fibrous sheet materialpartially stiffenedby a water soluble stiffening agent applied to one side and adapted tobe softened by moist heat and saturated with thermo-plastic material.

3. A shoe stiffener comprising fibrous material stiffened by a watersoluble stiffening agent and a thermoplastic agent, one of said agentsenveloping the other.

4. A shoe stiffener comprising fibrous material having one portionsaturated with a water soluble stiffening agent only and another portionsaturated with a thermoplastic agent only.

5; A shoe stiffener comprising fibrous sheet material having a portiontreated with a water soluble stiffening agent, and thermoplasticmaterial enveloping said treated portion and saturating'the remainder ofsaid material.

6. A shoe stiffener comprising fibrous sheet material, a water solublestiffening agent applied to one face of said sheet material, and athermoplastic enveloping said water soluble agent and with which saidfibrous material is saturated,

. 7. A shoe stiffening comprising fibrou sheet material partiallystiffened by .a water soluble material and saturated with thermoplasticmaterial.

8. A shoe stiffener comprising fibrous sheet material coated on one facewith glue, and

saturated with Montan' wax.

9. A shoe stiffener com material coated on one ace with glue, and

agents, as

rising fibrous sheet Saturated with Montan wax, the wax also coating theglued face. it

10. A shoe stiffener comprisin .fibrous sheet material partiallysaturate with a water soluble stiffening agent and then saturated withthermo-plastic material. 11. A shoe stiffener comprising fibrous sheetmaterial saturated throu h-a portion of its thickness with a water souble 'stiffening aglent, and'then saturated throughout with termo-plastic material.

12. In the manufacture of shoe stiffeners the steps which comprisecoating one face of fibrous sheet material with a water solublestiffening agent, and then immersing the sheet in melted thermo-plasticmaterial.

13. In the manufactureof shoe stiffeners, the steps which comprisecoating one face of fibrous sheet material with glue, permitting theglue to dry, and then saturating thematerial and coating the glued facewith thermoplastic material.

14. In the manufacture of shoe stifl'eners, the steps which comprisepartiall saturating fibrous sheet material with a sti ening agentsoftenable only when subjected to a solvent, permitting the material sotreated to harden, and then further saturating the material with asltliffening agent softenable when subjected to eat.

. 9 15. In the manufacture of shoe stiffeners, a

signature. A I

ALBERT L. 'GLAPP.

